Cyanobacteria: the Luxembourg Water Management Authority and the Luxembourg Institute of Science and Technology launch a mobile app

The Luxembourg Institute of Science and Technology (LIST), with the support of the Water Management Administration (Administration de la gestion de l'eau), has adapted the "Bloomin'Algae" mobile application so that users of Luxembourg's water areas can now report blooms of cyanobacteria, commonly known as "blue-green algae", to the authorities.

The proliferation, or 'blooms', of cyanobacteria in Luxembourg waters not only poses a health risk to bathers, domestic animals and livestock, but also undermines the environmental health of the aquatic ecosystem.

In order to gain a better understanding of this increasingly frequent phenomenon in Luxembourg, more field data is needed. To this end, the Bloomin'Algae application allows citizens to submit photos and the precise location of blue-green algae or suspected blue-green algae in just a few clicks. During the 2023 bathing season, the following sites are targeted: the Upper Sûre Lake, the ponds in Weiswampach and the Moselle river.

How does it work?

Download the Bloomin' Algae application, available for free on GooglePlay or in the App Store, then:

• Select "Luxembourg".
• Carry out your bloom observation in just 3 minutes:
  • Confirm the GPS coordinates of your smartphone as well as the date of the observation and describe your observation using the choices provided;
  •  Take one or more photos of your observation and then submit your report (immediately or later).
  • After checking and approval by a LIST expert, your contribution will be visible on the interactive map of Luxembourg.

The interactive map and additional information are available on the www.cyanowatch.lu website.

How do blue-green algae blooms form?

Planktonic cyanobacteria need light, heat and nutrients to develop. In Luxembourg, cyanobacteria generally bloom between August and October, in calm, nutrient-rich waters such as lakes, ponds and the Moselle. Generally speaking, episodes of cyanobacterial proliferation are being observed with increasing frequency on every continent.

Planktonic cyanobacteria blooms mainly occur in stagnant waters (lakes and rivers with slow currents) where there is an excessive input of nutrients, leading to plant proliferation and an imbalance in the ecosystem. To grow, cyanobacteria need high concentrations of nutrients, especially phosphorus, which can come from many sources: livestock effluents, compost, fertilisers spread on the soil, inadequately treated wastewater discharges, soil leaching during heavy rainfall. Reducing phosphorus and nitrogen inputs into surface waters remains the only sustainable way of protecting and/or restoring these ecosystems from planktonic cyanobacteria blooms. This is the aim of implementing the measures set out in the third management plan for the Luxembourg parts of the Rhine and Meuse international river basin districts. The modernisation of wastewater treatment plants, the reduction in the use of fertilisers in agriculture and the planting of riparian strips (Uferrandstreifen) along agricultural plots are among the measures contributing to reducing the input of nutrients into watercourses.

As the factors and processes that regulate cyanobacterial blooms are particularly complex, these phenomena are often difficult to predict.